This invention relates to engine arrangements. More particularly the invention relates to engine arrangements for blended wing-body aircraft.
The design of blended wing-body, or flying wing, aircraft requires somewhat different considerations than are necessary with conventional aircraft. Despite the promise of greater efficiency with such aircraft, there are a number of difficult structural and aerodynamic issues that need to be addressed before blended wing-body aircraft become commercially viable alternatives to conventional aircraft.
However, one problem with proposed designs is that the air flow which generates lift can be disrupted by the operation of the engine. A further problem with blended wing-body aircraft is that a large amount of power is required to move the aircraft control surfaces.
According to one aspect of this invention there is provided an engine arrangement for a blended wing-body aircraft, the arrangement comprising propulsion means for propelling the aircraft and drive means to drive the propulsion means, and the arrangement further including mounting means to mount at least said propulsion means in a location spaced from an upper or lower surface of said aircraft, and means for moving the propulsion means relative to the aircraft.
According to another aspect of this invention there is provided an engine arrangement for an aircraft, the arrangement comprising propulsion means for propelling the aircraft and drive means to drive the propulsion means, and the arrangement further including mounting means to mount at least said propulsion means in a location spaced from an upper or lower surface of said aircraft at a rear region of the aircraft. Preferably, the arrangement includes means for moving the propulsion means relative to the aircraft.
Preferably, the drive means is separate from the propulsion means. In one embodiment, the mounting means is adapted to mount only the propulsion means on said aircraft. The drive means may be adapted to be provided on, in, or under the aircraft. The propulsion means preferably comprises a fan comprising a plurality of fan blades, and may also include a turbine comprising a plurality of turbine blades. The turbine blades may be provided on the fan blades and are, preferably, substantially concentrically mounted on the fan blades. Advantageously, the turbine blades are provided radially outwardly of the fan blades.
In the preferred embodiment, the propulsion means comprises a tip driven fan, whereby the turbine blades are mounted on and extend radially outwardly from the outer ends of the fan blades.
The mounting means may comprise a pylon adapted to extend between the propulsion means and the aircraft.
Preferably, the propulsion means includes a housing or nacelle, the mounting means extending between the housing and the aircraft.
The drive means may comprise a gas generator operable to generate gas to drive the propulsion means. Preferably, the gas generator comprises a gas turbine arrangement comprising a compressor assembly, a combustor assembly and a turbine assembly in axial flow series.
A plurality of gas generators may be provided to drive the propulsion means.
A conduit arrangement may be provided between the drive means and the propulsion means. Preferably at least a part of the conduit arrangement extends through the mounting means. The conduit arrangement may further include a plenum chamber which, where there are a plurality of gas generators, may receive gas from each gas generator.
Valve means may be provided between the drive means and the propulsion means to prevent reverse flow of gas into the drive means.
Preferably, the valve means is provided between the drive means and the plenum chamber. Preferably, the valve means is provided immediately upstream of the plenum chamber.
Preferably, the moving means is adapted to move the propulsion means, preferably by tilting the propulsion means to assist in controlling the pitch of the aircraft. Additionally, or alternatively, the moving means may be adapted to move the propulsion means to control the yaw of the aircraft.
In one embodiment, the propulsion means is pivotally attached to the mounting means, and the moving means may be adapted to apply a force to the propulsion means. Preferably, the propulsion means is pivotally attached to the mounting means about an axis substantially parallel to the pitch axis of the aircraft, whereby the moving means may control the pitch of the aircraft.
In an alternative embodiment the propulsion means is rigidly attached to the mounting means and the latter is movable relative to the aircraft. Preferably the mounting means is tiltable about an axis substantially parallel to the pitch axis of the aircraft. Moving means may be provided to tilt the mounting means relative to the aircraft.
The moving means may comprise an hydraulic ram, motor driven gearing or aerodynamic members in the form of vanes extending internally and/or externally of the propulsion means.
Where the propulsion means is fixedly mounted to the mounting means, means may be provided between the mounting means and the aircraft and tiltably mount the mounting means on the aircraft. In this embodiment, the conduit extending through the mounting means may comprise a flexible portion to allow the conduit within the mounting means to move.
According to another aspect of the invention, there is provided an aircraft incorporating an engine arrangement as described above, wherein at least the propulsion means is provided towards the rear of the aircraft.
The drive means may be provided in, under, or on, the body of the aircraft. Where the drive means is provided in the aircraft, air inlet ducts extend from the drive means to an external surface of the aircraft and communicate with an air inlet opening therein. Preferably said air inlet opening is provided in the underside of the aircraft.